ASVAB practice test

ASVAB Electronics Information Practice Test

Circuits, components and electrical safety. Here are 10 ASVAB electronics information questions, each with the answer and the reason.

Updated 2026-11-14 by the Tigertest team. Covers eight of the CAT-ASVAB subtests in test order with the real time limits. Assembling Objects uses figures and is not included. Minimum AFQT scores vary by branch and change with recruiting needs.

1. 1.

   What is the unit of electrical resistance?

   • A.

     Volt

   • B.

     Ampere

   • C.

     Watt

   • D.

     Ohm

   Answer: D.

   Resistance is measured in ohms. The volt measures electrical potential, the ampere measures current, and the watt measures power.

2. 2.

   A circuit has a 12-volt source and a total resistance of 4 ohms. How much current flows?

   • A.

     3 amperes

   • B.

     8 amperes

   • C.

     16 amperes

   • D.

     48 amperes

   Answer: A.

   Ohm's law states V = I × R, so I = V ÷ R = 12 ÷ 4 = 3 amperes. Multiplying (48) or subtracting (8) applies the formula incorrectly.

3. 3.

   Which component stores electrical charge and releases it when needed?

   • A.

     Resistor

   • B.

     Capacitor

   • C.

     Inductor

   • D.

     Transistor

   Answer: B.

   A capacitor stores energy as an electric field between two plates. A resistor limits current, an inductor stores energy in a magnetic field, and a transistor switches or amplifies current.

4. 4.

   A diode allows electric current to flow

   • A.

     in both directions equally

   • B.

     in one direction only

   • C.

     only when it is heated

   • D.

     only in alternating current circuits

   Answer: B.

   A diode conducts in one direction and blocks current in the other, which is why diodes are used to convert AC to DC in rectifiers. A plain wire conducts equally in both directions.

5. 5.

   In a series circuit with three light bulbs, what happens if one bulb burns out?

   • A.

     The other two bulbs glow brighter

   • B.

     The other two bulbs stay lit at the same brightness

   • C.

     All of the bulbs go out

   • D.

     The fuse blows immediately

   Answer: C.

   In a series circuit there is only one path for current, so a burned-out bulb opens the circuit and stops all current. In a parallel circuit each bulb has its own path and the others would stay lit.

6. 6.

   What is the purpose of a fuse in an electrical circuit?

   • A.

     To stop excessive current

   • B.

     To store energy for later use

   • C.

     To increase the voltage

   • D.

     To convert AC to DC

   Answer: A.

   A fuse contains a thin metal strip that melts and opens the circuit when current exceeds its rating, protecting wiring and equipment. It does not store energy or change voltage.

7. 7.

   A transformer is used to

   • A.

     convert alternating current to direct current

   • B.

     raise or lower AC voltage

   • C.

     store electrical charge

   • D.

     measure electrical current

   Answer: B.

   A transformer uses two coils around a shared core to step AC voltage up or down. It works only with AC and does not rectify current; that is the job of a diode.

8. 8.

   In standard US residential wiring, which wire color indicates the ground wire?

   • A.

     Black

   • B.

     White

   • C.

     Red

   • D.

     Green or bare copper

   Answer: D.

   Ground wires are green or bare copper. Black and red are hot wires carrying current, and white is the neutral wire that returns current to the panel.

9. 9.

   How does alternating current (AC) differ from direct current (DC)?

   • A.

     AC reverses direction repeatedly

   • B.

     AC flows only in batteries

   • C.

     AC cannot be transmitted over long distances

   • D.

     AC has no voltage

   Answer: A.

   In AC the current reverses direction many times per second (60 cycles, or 120 reversals, per second in the US), while DC flows steadily in one direction. Batteries supply DC; wall outlets supply AC.

10. 10.

    Which instrument is used to measure electric current?

    • A.

      Voltmeter

    • B.

      Ohmmeter

    • C.

      Ammeter

    • D.

      Wattmeter

    Answer: C.

    An ammeter measures current in amperes and is connected in series with the circuit. A voltmeter measures voltage across two points and an ohmmeter measures resistance.